That's where my thinking was 6 years ago. I thought hot water was a meaningful opportunity for energy savings, and electric water heaters were MUCH more expensive to operate.
Then I started looking at bills. At the time I was selling audits rather than performing them, so I could see as many as many as 4 energy bills a day. I tried an experiment I called "see the water heater" - where I attempted to determine the heater type by looking at the energy bill.
I couldn't do it. When people had low electric use I'd guess gas, then go to the basement and be wrong.
And when I did higher level analysis - attempts to disaggregate cost showed a couple things. First - hot water costs less than most imagine. Second - the true electric water heater factor over gas was about (4/3x) not (9/3x). My schema began to change.
Let's consider the savings opportunity:
So WHERE did the science go wrong? Oversimplifying. Let's explore a couple direct and indirect external costs not accounted for that drag the opportunity down:
I am loathe to make recommendations real world evidence does not support. I need my predictions to be accurate. Allowing bogus hot water savings into my models will make the whole model fail.
And NOW let's factor external costs most don't consider:
I am also loath to make recommendations that could kill people. To me energy savings is the result, not the driving force. Good design considers operational and maintenance simplicity, health of occupants, control, and removing impediments to future improvements.
Hopefully I've started creating a picture of why I think unsealed combustion appliances are S-T-U-P-I-D. Get rid of stupid water heaters, the real energy savings opportunities are elsewhere. Stop chasing pennies when there are dollars just as easy to grab blowing away.
That's unfortunate, fossil methane production is between crude oil and coal for carbon-footprint, the glut of new wells is why it's cheap but the long-term affect of that will be to keep heating the ocean, the air isn't as big a deal, most of the heat is going to melting ice-sheets now and the ocean, not the atmosphere and we're gaining 34% more heat per square meter than 1990 on a steepening curve.
This is our report card, it's the greenhouse gas page and radiative forcing, aka greenhousing, costs are the wrong metric to use to deal with this: http://www.esrl.noaa.gov/gmd/aggi/aggi.html
So I guess that is the math that Ted needs to see. Sorry Ted but I totally agree with Paul and Bob. Of course this whole debate is completely based on local utility costs. If you live near a hydroelectric dam and have off peak and non-tiered electric pricing it probably can be cheaper. That's not where I live. And as someone who has done well over 2000 energy audits I can play "find the electric water heater" and win. In my area,homes with electric water heaters have electric bills that are double that of a NG DWH.
I don't need to see made up math. I used to make some pretty poor conclusions using it, now I know better.
Clocks have been used on electric water heaters for DECADES to avoid heating tanks with high cost electricity. This is nothing new that should surprise people with tou rates.
I definitely don't need an absurd and hypothetical example of excluded middle with no expertise behind it as example that gas possibly saves less than a Starbucks coffee a week.
I'm not saying electricity costs less, I'm saying the difference is usually irrelevant. And hypothetical situations where you game all the inputs to your advantage to justify claims of savings for a thing you sell, without any documentation to actually PROVE your self serving position, only lead to questions of integrity, not conclusions about design.
Show me the energy use and cost before on electric.
It doesn't seem like any math or anything else is going to make you feel differently. That's fine. That is kinda the point of websites like this - we can all agree to disagree. As much as many of like to talk about everything we do as "building science", you can have 10 different people look at a house and find 10 different things that they think are the number one priority.
Anecdotal reports on lighting have been either they change them all at once, or they change them as the incandescent fail.
Those who change them all at once tend to report surprise at actually being able to see the savings. Obviously those who change over time don't.
IMO, the reasons to change from CFL to LED are not energy reasons - the delta is too small. (Better light, longevity, better dimming).
Like going to the gas pump, if you do it twice a week you get numbed to it. If you do it once a month it starts getting annoying. When you drive a Tesla and switch back for a while, going to the gas station seems a completely stupid thing to do. CFL longevity has made changing bulbs pretty annoying, and soon that perspective will shift such that it'll seem stupid not to just go LED.
Switching from Edison to LED lighting is about the same amount of energy savings as going from NG to electric water heater. NG with a tank runs about $200/yr vs $500 for electric tank. $300/yr is close to what most residential customers would save switching from Edison to LED. Is a $300/yr savings significant to you?
For some reason when I built my house all of my can lights had 100w bulbs in them, the kitchen has over 20 cans and 3 hanging lights, I did notice an electric bill change when I went to led.... About 25%...
There are other considerations that can trump this discussion, at least this is true in NY.
The money stream funding the home performance programs comes from utility companies, mostly electric companies. Their inspiration is reducing electric demand so they need fewer power plants. Adding electric water heaters defeats this purpose. Conversely, to the consumer who is looking at 1500 for a power vented water heater or $400 for an electric one and the reason for the change is combustion safety, there is big driver toward electric. Especially for elderly singles or couples who use very little hot water.
Interestingly, with respect to Tankless Water Heaters, our local utility was offering rebates on power vented water heaters and higher efficiency furnaces & Boilers, but they would not give the rebate on tankless. As has been indicated here, Tankless is much higher AFUE than power vented, so that didn't make sense to me. I finally cornered the right guy and asked why. I was told, the tankless units are 150000+ btu heaters, their consumption is so high that the pipelines gas companies have in some neighborhoods could not supply several dozen of them on one pipe. The consumers likely would not know how much supply a utility could provide to their particular branch line, so they would have no way of knowing if they were installing something that would not work. Scary thought.